J/A+A/568/L8 VUDS extreme emission line 0.2≲z≲0.9 galaxies (Amorin+, 2014)
Discovering extremely compact and metal-poor, star-forming dwarf galaxies out to
z∼0.9 in the VIMOS Ultra-Deep Survey.
Amorin R. , Sommariva V., Castellano M., Grazian A., Tasca L.A.M.,
Fontana A., Pentericci L., Cassata P., Garilli B., Le Brun V.,
Le Fevre O., Maccagni D., Thomas R., Vanzella E., Zamorani G., Zucca E.,
Bardelli S., Capak P., Cassara L.P., Cimatti A., Cuby J.G., Cucciati O.,
de la Torre S., Durkalec A., Giavalisco M., Hathi N.P., Ilbert O.,
Lemaux B.C., Moreau C., Paltani S., Ribeiro B., Salvato M., Schaerer D.,
Scodeggio M., Talia M., Taniguchi Y., Tresse L., Vergani D., Wang P.W.,
Charlot S., Contini T., Fotopoulou S., Lopez-Sanjuan C., Mellier Y.,
Scoville N.
<Astron. Astrophys. 568, L8 (2014)>
=2014A&A...568L...8A 2014A&A...568L...8A
ADC_Keywords: Galaxies, spectra ; Redshifts ; Abundances ; Surveys
Keywords: galaxies : evolution - galaxies : high redshift - galaxies : dwarfs -
galaxies : abundances - galaxies : starbursts
Abstract:
We report the discovery of 31 low-luminosity (-14.5≳MAB(B)≳-18.8),
extreme emission line galaxies (EELGs) at 0.2≲z≲0.9 identified by
their unusually high rest-frame equivalent widths
(100≤EW[OIII]≤1700Å) as part of the VIMOS Ultra Deep Survey
(VUDS). VIMOS optical spectra of unprecedented sensitivity
(IAB∼25mag) along with multiwavelength photometry and HST imaging
are used to investigate spectrophotometric properties of this unique
sample and to explore, for the first time, the very low stellar mass
end (M*≲108M☉) of the luminosity-metallicity (LZR) and
mass-metallicity (MZR) relations at z<1. Characterized by their
extreme compactness (R50<1kpc), low stellar mass and enhanced
specific star formation rates (sSFR=SFR/M*∼10-9-10-7yr-1), the
VUDS EELGs are blue dwarf galaxies likely experiencing the first
stages of a vigorous galaxy-wide starburst. Using Te-sensitive direct
and strong-line methods, we find that VUDS EELGs are low-metallicity
(7.5≲12+log(O/H)≲8.3) galaxies with high ionization conditions
(log(qion)≳8cm/s), including at least three EELGs showing
HeIIλ4686Å emission and four extremely metal-poor (≲10%
solar) galaxies. The LZR and MZR followed by VUDS EELGs show
relatively large scatter, being broadly consistent with the
extrapolation toward low luminosity and mass from previous studies at
similar redshift. However, we find evidence that galaxies with younger
and more vigorous star formation --as characterized by their larger
EWs, ionization and sSFR-- tend to be more metal poor at a given
stellar mass.
Description:
The Vimos Ultra Deep Survey (VUDS) is a deep spectroscopic legacy
survey of ∼104 galaxies carried out using VIMOS at ESO-VLT. This
survey is aimed at providing a complete census of the SF galaxy
population at 2≲z≲7, covering ∼1deg2 in three fields: COSMOS,
ECDFS, and VVDS-2h. The VIMOS spectra consist of 14h integrations in
the LRBLUE and LRRED grism settings, covering a combined wavelength
range 3650<λ<9350Å, with a spectral resolution R∼230. Data
reduction, redshift measurement, and assessment of the reliability
flags are described in detail in the survey and data presentation
paper (Le Fevre et al. 2014arXiv1403.3938L 2014arXiv1403.3938L).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 104 31 Emission line fluxes and reddening
table2.dat 90 31 Derived physical properties of EELGs in VUDS
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See also:
VII/265 : COSMOS Morphological Catalog (V1.1) (Tasca+ 2009)
III/250 : The VIMOS VLT deep survey (VVDS-DEEP) (Le Fevre+ 2005)
J/ApJ/743/77 : Extremely metal-poor galaxies in SDSS (Morales-Luis+, 2011)
J/ApJ/742/111 : Extreme emission-line galaxies in CANDELS (van der Wel+, 2011)
J/ApJ/728/38 : AEGIS: demographics of X-ray and optical AGN (Yan+, 2011)
J/A+A/512/A12 : VLT/VIMOS spectroscopy in GOODS-South field (Balestra+, 2010)
J/A+A/495/53 : Physical properties of VVDS galaxies (Lamareille+, 2009)
J/ApJ/675/234 : Stellar mass in galaxies 0<z<4 (Perez-Gonzalez+, 2008)
J/ApJS/153/429 : SDSS strong emission line HII galaxies (Kniazev+, 2004)
J/A+A/428/1043 : Redshifts from VIMOS VLT Deep Survey (Le Fevre+, 2004)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 I10 --- ID [510146174/5120568170] VUDS ID number
12- 15 F4.1 zW/m2 F(3727) line flux [OII]3727 in 10-18ergs/s/cm2
17- 19 F3.1 zW/m2 e_F(3727) ? error in [OII]3727 line flux (1)
21- 24 F4.1 zW/m2 F(3868) ? line flux [NeIII]3868 10-18ergs/s/cm2
26- 28 F3.1 zW/m2 e_F(3868) ? error in [NeIII]3868 line flux (1)
30- 33 F4.1 zW/m2 F(Hg) ? Hγ line flux in 10-18ergs/s/cm2
35- 37 F3.1 zW/m2 e_F(Hg) ? error in Hγ line flux (1)
39- 41 F3.1 zW/m2 F(4363) ? line flux [OIII]4363 in 10-18ergs/s/cm2
43- 45 F3.1 zW/m2 e_F(4363) ? error in [OIII]4363 line flux (1)
47- 50 F4.1 zW/m2 F(Hb) Hβ line flux in 10-18ergs/s/cm2
52- 54 F3.1 zW/m2 e_F(Hb) error in Hβ line flux (1)
56- 60 F5.1 zW/m2 F(4959) line flux [OIII]4959 in 10-18ergs/s/cm2
62- 64 F3.1 zW/m2 e_F(4959) error in [OIII]4959 line flux (1)
66- 70 F5.1 zW/m2 F(5007) line flux [OIII]5007 in 10-18ergs/s/cm2
72- 74 F3.1 zW/m2 e_F(5007) error in [OIII]5007 line flux (1)
76- 80 F5.1 zW/m2 F(Ha) ? Hα line flux in 10-18ergs/s/cm2
82- 84 F3.1 zW/m2 e_F(Ha) ? error in Hα line flux (1)
86- 88 F3.1 zW/m2 F(6584) ? line flux [NII]6584 in 10-18ergs/s/cm2
90- 92 F3.1 zW/m2 e_F(6584) ? error in [NII]6584 line flux (1)
94- 97 F4.2 --- c(Hb) Reddening constant
99-102 F4.2 --- e_c(Hb) error in reddening constant
104 A1 --- f_c(Hb) [ab] Method for the reddening constant (2)
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Note (1): Flux errors have been derived following Perez-Montero et al.
(2003MNRAS.346..105P 2003MNRAS.346..105P) and Amorin et al. (2012ApJ...749..185A 2012ApJ...749..185A).
No extinction correction has been applied to these fluxes.
Note (2): Blank values indicates c(Hβ) values derived from
Hα/Hβ or Hγ/Hβ ratios, whenever possible.
Otherwise c(Hβ) values obtained from the SED best-fitting, with
indications as follows:
a = computation of c(Hβ) from emission lines is not possible because of
the lack of lines.
b = the corresponding line ratio produces a negative extinction correction
(i.e., Hα/Hβ<2.82 or Hγ/Hβ<0.47, assuming Case B
recombination with Te=2x104K, ne=100cm-3)
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 10 I10 --- ID VUDS ID NUMBER
12- 21 F10.6 deg RAdeg Right Ascension J2000.0
23- 32 F10.6 deg DEdeg Declination J2000.0
34- 39 F6.4 --- z [0.2/0.9] Spectroscopic redshift
41- 46 F6.3 mag Imag [23.3/25.4] I-band apparent AB magnitude
48- 52 F5.1 mag BMag Resft-frame B-band absolute AB magnitude
from SED best-fitting
54- 57 F4.2 Msun M* Stellar mass from SED fitting (3)
59- 62 F4.2 Msun E_M* Positive uncertainty in stellar mass (4)
64- 67 F4.2 Msun e_M* Negative uncertainty in stellar mass (4)
69- 73 F5.2 [Msun/yr] logSFR Logarithm of star formation rate (5)
75- 78 F4.2 [Msun/yr] e_logSFR Uncertainty in logSFR (6)
80- 83 F4.2 [-] Ab(O) [7.5/8.4] Gas-phase metallicity [12+log(O/H)]
85- 88 F4.2 [-] e_Ab(O) 1σ uncertainty in metallicity (6)
90 A1 --- n_Ab(O) [ds] Method for metallicity derivation (7)
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Note (3): A Chabrier IMF was adopted.
Note (4): They account for the statistical uncertainties in the SED fitting,
where our 1σ errors (caused by photometric uncertainties) were
computed by considering all the solutions within a reduced
χ2min+1 (Castellano et al. 2014A&A...566A..19C 2014A&A...566A..19C).
Note (5): It is computed from Hα or Hβ luminosity and adopting
the Kennicutt (1998ApJ...498..541K 1998ApJ...498..541K) calibration (by assuming a
Chabrier et al. (2003PASP..115..763C 2003PASP..115..763C) IMF and a theoretical ratio
Hα/Hβ=2.82).
Note (6): It accounts for the propagated errors in line fluxes and reddening
Note (7): Flag as follows:
d = metallicity derived through the direct Te method following
Hα et al. (2008MNRAS.383..209H 2008MNRAS.383..209H).
s = metallicity derived through the R23 calibration McGaugh
(1991ApJ...380..140M 1991ApJ...380..140M) scaled to the direct method using the linear
relation presented by Lamareille et al. (2006A&A...448..907L 2006A&A...448..907L)
(see also Perez-Montero et al. 2013A&A...549A..25P 2013A&A...549A..25P)
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Acknowledgements:
Ricardo Amorin <ricardo.amorin (at) oa-roma.inaf.it>
(End) Ricardo Amorin [INAF], Emmanuelle Perret [CDS] 22-Aug-2014